Siri can not hear me in iOS 11.4

Is anyone else having issues with Siri on iOS 11.4?

I have an iPhone 8plus. I don't have a case or screen protector on the phone, it is completely bare. I have tested the microphones using Apples recommendation (Voice recorder for bottom mic, front facing video for ear piece mic and rear camera video for rear mic) and all mics were working perfectly.

The issue is that often when I use Siri she either doesn't hear me at all or only hears part of what I said. Also the "Hey Siri" command isn't very sensitive to the point that I have to shout at my phone for it to respond. This morning when I was getting ready for work I literally had to shout at her to get her to give me the weather. When I first got this phone I was extremely pleased by how well "Hey Siri" worked and how sensitive the mics were but now it's the complete opposite, it's terrible and frankly useless.

Any help would be much appreciated!

Kind regards,

Jay